Overview

Mapping of compiled Waze events from April 2017 to November 2018 in Bellevue, WA. Events within 6 miles of the center of Bellevue were included in this initial work, and the ‘city’ field in the Waze data was used to remove events where were labeled as being outside of Bellevue. One of the next steps will be to clip to the city boundary shapefile. In addition, the Bellevue road network has not yet been incorporated in these maps. A base layer derived from Open Street Maps is used for these maps.

First, looking at frequency of all Waze incident reports by street name. Of all 477,284 Waze incident reports, 29,014 (6.08%) had no value provided for ‘street’ in the data. Of the 12,906 crash reports, 2,125 (0.45%) had no value provided for ‘street’.

Ten most frequent street names for all Waze incident reports in study period
Street Frequency
I-405 S 98,344
I-405 N 49,547
I-90 W 43,381
I-90 E 28,848
SR-520 W 28,359
W Lake Sammamish Pkwy SE 11,674
I-405 N Exp Toll Ln 11,069
SR-520 E 9,492
I-405 S Exp Toll Ln 9,420
Coal Creek Pkwy SE 8,349

In the Waze data, there are two ways to make an initial filter to omit roads which are not in the jurisdiction of Bellevue: to filter by street names, and also to filter by road class. Waze uses their own road classification system; interstates are all class ‘3’ in the Waze system.

Here we filter the Waze data by excluding I-405, I-90, as well as SR-520 (assuming this is not in Bellevue jurisdiction), and by omitting any additional events on class 3 roads. Filtering by name effectively removes nearly all class 3 roads. Some Waze events missing a street name and with an incorrect road class may still appear on the interstates after this filtering process; a GIS approach to snap Waze events to road segments will also be necessary.

Ten most frequent street names for all Waze incident reports, omitting highways, in study period
Street Frequency
W Lake Sammamish Pkwy SE 11,141
Coal Creek Pkwy SE 8,198
to I-405 N / Everett 7,649
Bellevue Way SE 7,207
148th Ave NE 6,357
to I-405 S / Renton 5,804
148th Ave SE 5,765
NE 8th St 4,171
Richards Rd 3,785
112th Ave SE 3,419

The Waze incidents remaining after filtering out highway events are summarized in the table below by alert type and subtype. Not all alerts have a subtype provided.

Heat maps

The following heat maps show 2-D kernel density estimates of incident frequency. Warm colors indicate high frequency, cool colors show lower frequency. Maps are shown with and without individual incidents plotted for clarity.

All Waze crash reports

12,906 Waze crash reports.

Waze crash reports, omitting highways

3,677 Waze crash reports, after filtering out highways.